JPS6358303B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improved hydraulic limited drive gear train for use in limited slip differentials in motor vehicles and the like.

An automobile differential transmits equal drive torque to the left and right drive shafts. This characteristic of transmitting equal torque to both wheels of a vehicle is undesirable when one wheel has more driving force than the other.

Various types of slip-limiting actuators have been developed to allow motor vehicles to operate on slippery surfaces. When the vehicle changes direction,
The slip limiting actuation device is used to transmit effective torque to the left and right drive wheels while allowing a difference in rotational speed so that the vehicle can travel around curves without causing the tires to slip.

A hydraulic system is disclosed in U.S. Pat. No. 4,084,654, dated April 18, 1978, entitled "Hydraulic Vehicle Slip Limiting Gear Train." In that device, oil is used not only to limit the driving force of the differential gear train, but also to cool the gear train. The limited slip gear train of this patent utilizes fluid resistance to limit the driving force of the planetary gear train. However, in this patented device, the side plate is formed to fit snugly over the tips of the gears, forming a chamber that surrounds the peripheries of these gears without any gaps. Moreover, since the planetary gears used in this limited-slip gear train are mounted on bearings that are supported so as not to move, the spacing between the planetary gears relative to the chamber wall is fixed and does not change.

As an example of the prior art of limited-slip differentials that utilize frictional forces, Aspro's Detroit Automotive Division, located in Warren, Michigan, USA,
A gear-type mechanism is produced that uses a pair of intermeshed roller-type helical pinion gears. Left and right drive axles are connected to each sun gear of the coaxially aligned sun gear pair. One of these sun gears has 1
The two pinions engage to create a differential interlock. Because of the geometry of the gears of the mechanism, the pinions are pressed against the chamber wall of the pocket-shaped chamber surrounding them, so that rubbing friction occurs between the pinions and the pocket. As with any prior art device,
The rubbing action of friction alone cannot achieve complete slip restriction.

One object of the present invention is to provide a limited-slip gear train that is relatively inexpensive and has a simple structure, and is used in an automobile axle differential or differential power distribution device.

Another object of the present invention is to provide a hydraulic limited slip gear train for a vehicle that has uniform torque transmission characteristics in both forward and reverse directions.

The foregoing and other objects of the present invention are achieved by an improved hydraulic limited slip gear train for use in power distribution systems, differentials, and the like.
The present invention provides improved performance and hydraulic slip limitation for planetary differential gear trains. The planetary gear train has an outer fluid-tight housing surrounding an inner housing.
Apparatus is provided for supplying fluid into the inner housing and maintaining the inner housing generally fluid-filled. The inner housing includes a planetary gear train, the planetary gear train having one sun gear;
It includes a plurality of planetary gears and internal gears, all of which lie in the same plane. Plates are provided on opposite sides of the gear in close abutting relationship, portions of both plates surrounding the periphery of the gear to form a chamber containing the planetary gear. both plates include coaxially aligned fluid inlet and outlet holes;
These fluid holes are located parallel to the gear teeth but a distance from the gear engagement point. Fluid is conveyed by the gear from the fluid inlet hole to the meshing point of the gear, where the fluid squeezing action creates a force that resists the movement of the gear. The improved limited slip gear train of the present invention includes a device for moving the planetary gears to position their tips in close abutting relation to the wall of the chamber in which the gears are housed. As the teeth of the gear move towards the chamber wall, the flow of fluid between the teeth is restricted, thereby increasing the resistance force on the gear, thus improving the slip restriction of the gear train. The friction between the tooth tip of the gear and the chamber wall is
In addition to said resistance due to the squeezing action of the fluid,
Creates resistance to the movement of gear teeth. Devices for movably positioning gears include devices for loosely fitting planetary gears into bearings.

According to another feature of the invention, one or both of the planetary gears in the pair are not mounted on bearings, so that they float within the gearbox. The various forces acting on the planetary gear force the tooth tips of the planetary gear against the walls of the gear chamber, creating a close abutment between the tooth tips and the chamber wall. Pairs of planetary gears with opposite orientations are alternately arranged between the inner ring gear and the sun gear. Half of these planetary gear pairs operate in one orientation and the other half in another orientation. Therefore, improved slip restriction and smoother and more uniform operation of the gear train can be achieved whether the slip-limiting gear train is moved in the forward or reverse direction.

The present invention is an improvement on the limited gear train drive disclosed in U.S. Pat. No. 4,084,654.

The improved limited-slip gear train drive for vehicles provided by the present invention is suitable for application to differential gear trains for automobiles, such as differentials of power distribution devices used to connect and disconnect power to axles. Particularly suitable for FIG. 1 shows an axle differential as a typical application example. Although the present invention is advantageously used in front wheel drive systems, it is equally useful in conventional rear wheel drive systems. Driving power is supplied to the axle differential drive 10 via a drive shaft 12 from a suitable drive source, such as an automobile engine coupled to a suitable power transmission. The first and second axles 14, 15 are driven by an axle differential 10. Axles 14, 15 drive respective wheels 16, 17. When the vehicle travels in a straight line, the differential device 10 rotates both wheels 16, 17 at a constant speed. When the vehicle travels around a curve, the differential 10 causes the axles to rotate at different speeds.

Referring to FIG. 2, there is shown a hydraulic limited slip axle differential 20 having a structure similar to that disclosed in the aforementioned U.S. Pat. No. 4,084,654. It is clear that the present invention is also suitable for application to a power distribution device for a vehicle. Outer housing 22 accommodates inner housing 24. The inner housing 24 receives drive power from a drive shaft 26 which is coupled to a hypoid gear 28 via a conventional coupling gearing 30. The inner housing 24 is connected to the hypoid gear 28 by means of bolts 32 (one of which is shown as a representative).
Fixed. Inner housing 24 is mounted on bearing arrangement 34 by any suitable means. Axles 36 and 37 are driven by differential 20. A planetary differential gear set 40 is contained within the inner housing 24.

FIG. 3 shows the components of the planetary gear set 40.
The internal gear 50 includes an outwardly projecting peripheral flange 52 which is sandwiched between the hypoid gear 28 and the inner housing 24 in a sandwich manner. Ring gear 50 couples power from drive shaft 26 to inner housing 24 . planetary gear 60,
61 multiple groups (one group is shown as a representative)
engage ring gear 50 and sun gear 62, respectively. Note that the sun gear 62 has an inner spline hole 63 that engages with the axle 37 forming a spline shaft.

Left axle cover plate 70 has an internal spline hole 71 that engages axle 36 . The right axle cover plate 80 has an upwardly projecting center portion 82, the upper surface of which abuts the inner surface of the left axle cover plate.
The left and right axle cover plates 70 and 80 are bolted together by bolts 85 (one of which is representatively shown) that engage nuts 84 (one of which is representatively shown). As shown, axle cover plate 80 has a chamber therein surrounding sun gear 62 and a plurality of planet gears 60,61.
Both axle cover plates are bolted together and
A planetary gear box containing the paired planetary gears 60 and 61 is formed. The planetary gears 60 and 61 have bearing sleeves 90 made of bearing materials such as aluminum, nickel, and bronze (two of which are representatively shown).
rotate around. The outer diameter of the sleeve bearing 90 is smaller than the inner diameter of the axial bore 92 passing through the planetary gears 60, 61. Since the sleeve bearing 90 is loosely fitted, the rotation of the planetary gears 60, 61 can drift. The right axle cover plate 80 is made of, for example, a Teflon-impregnated cast iron material or a hardened zinc-coated material, while the gears are made of, for example, No. 4330 alloy steel with a surface hardening treatment. Cover plate 80 due to the use of different materials
This can prevent the occurrence of gear galling.

Each side plate making up the cover plate 80 is provided with oil inlet and outlet holes 96, some of which are coaxially aligned between the two plates 70 and 80 to provide gear cooling. Remaining oil hole 96
are not aligned on the same center line. However, all of these oil holes are arranged in contact with and parallel to the tooth flank of one of the gears of the planetary differential gear. The role of these non-aligned oil holes is
These oil holes allow oil or other suitable fluid to be introduced into the gaps between the teeth of the gear so that the oil is carried on the teeth of the gear and reaches the point of engagement between this gear and the adjacent gear. The goal is to make it happen. At the meshing point, the gears act as gear pumps, squeezing out the oil so that the oil is squirted in all directions around the meshing teeth of both gears. As a result, the oil resists rotation of the gear due to fluid resistance. plates 70 and 8
0 is in tight contact with the tip surface of the gear, and chamber 1
00, 101, 102, and 103 (representatively shown) are formed in these plates so as to surround the tip surfaces of the gear teeth. The oil hole in the side plate is not at the meshing point between adjacent gears, but is away from the meshing point, so the pumping action of the oil does not occur directly at the oil hole, but rather away from the oil hole. Since this occurs in a tightly sealed area, resistance to the movement of the gear will be created. The planetary gears 60, 61 can also be used without sleeve bearings. This allows the planet gear to float within the chamber formed by the plates 70, 80, which has the same effect as loosely mounting the planet gear on a sleeve bearing.

When one of the axles 36, 37 rotates at a speed different from the speed of the other axle, the ring gear 52 connected to the axle 36 rotates at an angular speed different from the angular speed of the sun gear 62 connected to the axle 37. . Since there is a difference in angular velocity between the ring gear and the sun gear, rotation occurs in the planetary gears 60 and 61. The rotation of these planetary gears is resisted by the fluid as described above. If the center points 60', 61' of the planetary gears are not restrained to rotate around a fixed axis, the planetary gears 60, 61 will move in response to the reaction force that tries to separate the meshed gears, and the torque will increase. A reaction force will be exerted on each element gear of the differential gear train.
The pressure angle of the planetary gear is chosen to be 25 degrees. standard
Compared to a gear with a pressure angle of 25 degrees, a gear with a pressure angle larger than 25 degrees not only has a stronger rotational force, but also has a greater force trying to separate the meshing gears. Since the planetary gears can move freely in the respective chambers in which they are housed in response to the separation force and torque reaction force, the tips of the teeth of these planetary gears, that is, the outer peripheral surface of the teeth, are pressed against the inner surface of the chamber wall. It forms a close contact relationship with various parts of the inner surface. This abutting relationship further restricts fluid flow within the chamber and increases the frictional force between the gear and the chamber wall, thereby increasing the resistance against the gear train.

FIG. 4 shows pairs 60 of planetary gears arranged alternately,
61 and the pair 110 and 111 are shown. As is clear from the figure, the adjacent chamber is connected to the side plate 82.
Since the chambers are formed symmetrically within the chamber, the walls of adjacent chambers are also arranged symmetrically. Both gears belonging to each adjacent pair have opposite directions of rotation with respect to the sun gear and the inner ring gear.
The right side plate 80 has planetary gearboxes arranged such that the planetary gears form a set of circumferentially spaced gear pairs around the sun gear 62.

The rotational axes of the gear pairs belonging to one set are each on a common straight line 63, 113, and these straight lines are slightly displaced as a result of the movement of the gear center. Some of these common lines take one orientation, while others take a different, opposite orientation. This symmetrical arrangement of the gear pair sets results in essentially the same overall resistance force whether the gears rotate relative to each other in one direction or in another direction. . In one direction of rotation, a pair of gears produces a certain amount of resistance. In opposite directions of rotation, this same gear pair produces different amounts of drag. The alternating alignment of the planetary gear pairs provides smooth engagement of the differential gears and reduces the tendency for the gears to suddenly jam. As shown in FIG. 4, by arranging alternating gear pairs symmetrically, whether the gears move in one direction or another,
These sets of gear pairs collectively produce similar resistance forces.

In FIG. 4, the center 11 of the planetary gears 110, 111
0', 111' are not supported by bearings, ie they float in the chamber. As the center of the gear moves in response to a force exerted on the gear, the tips of the teeth of the gear are free to contact the walls of the chamber, increasing the resistance to movement of the gear and also increasing the gear slip restriction.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of a typical automotive differential. FIG. 2 is a sectional view of an automobile differential incorporating a hydraulic slip limiter. FIG. 3 is an exploded view of a portion of the improved hydraulic limited slip gear train. FIG. 4 is a plan view of a subassembly of a planetary gear train according to the present invention. 20...Fluid pressure type slip limiting gear train, 22...
...Outer housing, 24...Inner housing, 5
0...Inner ring gear, 60, 61, 110, 1
11... Planetary gear train, gear pair, gear pair set, planetary gear, 60', 61', 110', 111'... Rotating shaft, 62... Sun gear, 63, 113... Common line, 70, 80...Plate device, 90...Device (installed in a clearance fit relationship), clearance fit bearing, 9
6...Fluid inlet hole, fluid outlet hole, 100,10
1, 102, 103... Fluid-filled state (chamber), 110, 111... Floating planetary gear.

Claims (1)

[Scope of Claims] 1. An improved hydraulic limited slip gear train for use in a power distribution device including a differential, comprising a fluid-tight outer housing, an inner housing, and a planetary gear housed within the inner housing. with columns;
The gear train includes a sun gear, a plurality of planet gears, and an inner ring gear, which are positioned on opposite sides of the planet gear in close abutting relationship with the gears and at the periphery of the gears. In a gear train in which the inner housing is generally kept fluid-filled, the planetary gear teeth are provided with a plate arrangement closely surrounding the inner housing, in order to increase the drag of the fluid acting on the gears. comprising means for mounting at least one of the planetary gears in a clearance fit relationship such that an end can move into close abutting relationship with a plate arrangement surrounding the gears, said plate arrangement being arranged in a clearance fit relationship with said gears; The fluid acting on the meshing points of these gears and the teeth of the planetary gear is arranged around the periphery of the gears in a parallel relation to the teeth of the gears, but at a distance from the meshing points of the gears. fluid inlet holes and fluid outlet holes for feeding between said at least one planetary gear and said plate arrangement brought into closer spacing to said plate arrangement by said clearance fit arrangement to increase pressure; An improved hydraulic slip limiting gear train, comprising: an improved fluid pressure slip limiting gear train, thereby increasing the drag force of fluid acting on these planetary gears in order to realize fluid pressure slip limiting. 2. The planetary gears form a set of gear pairs spaced apart on a circumference around the sun gear, each planetary gear has a rotation axis, and the rotation axis of the planetary gears belonging to one set is set in advance. lying on one common line with a defined orientation, such common line for half of said planetary gear set having one orientation and the other half having an orientation different from and opposite to this orientation; Therefore, the torque load acting on each set increases the fluid drag force by the same amount no matter which direction the planetary gear rotates, and reduces the fluid pressure limiting force by the same amount in either direction of rotation. A gear train drive device according to claim 1. 3. The gear train drive of claim 1, wherein said mounting device includes a clearance fit bearing for said at least one planetary gear. 4. The gear train according to claim 1, wherein at least one of the planetary gears is floating.